I like where (I think) Pavel is going with the swings ... overspeed (in S&S, he renamed these "shadow swings") two-hand / double swings, and floater single swings. This has been my default for years. When training general and special population military, I use overspeeds (shadows) to get the guys off of sit ups, but remain able to max out the event on the tests. Training sit ups regularly only ends with low back pain. Shadow swings was my answer. In addition to the sit up maintenance / improvement, it is just unreal what low-rep sets of heavy, shadow swings do for mid-line strength and power.
It takes a while to properly learn these, and forging the motor program for the floater (regular) swing FIRST is important. Meaning that a new student (in my dojo) has to drill the floater swing for a at least 3 months before we introduce them to the shadow swing version. And that means ignoring their pleas to play with the shiny new object that the guy (who's put his time in) next to them gets to play with. For some, it's a quicker progression, but 3 months seems to do it for most. If you introduce the shadow swing too early, your will degrade the motor program for the basic swing.
My version of the shadow swing is to cue the student to stop the ascent of the bell at about the 45 degree down angle, and reverse it back into the hinge. A properly executed shadow swing successfully plays the body in a tug of war between the posterior chain (hip snap) and anterior chain /lats (stab & hike). Watching the evolution (and facial expressions) of a student learning the shadow swing is a beautiful thing - like a sculpture in progress.
All of my students, myself included, use the shadow as the default swing when we have two hands on the bell, or double bells. If I program single swings, the default is as described in S&S. Great stuff!
Your miles may vary, but I have been exploring this for too long to think otherwise.
S&S is a definite read for anyone training with KBs.
-Al